Cisco Systems has released software updates to fix critical issues that could allow attackers to compromise digital encoders, unified computing system management servers and Firepower 9000 series security appliances.

The Cisco Modular Encoding Platform D9036, a hardware appliance that provides multi-resolution, multi-format encoding for applications that require high video quality, has a hard-coded static password for the root account.

This is the highest privileged account on the operating system and is created at installation time. The account and password cannot be changed or deleted without impacting the functionality of the system, Cisco said in an advisory.

The existence of a root account accessible over SSH (Secure Shell) with a known and unchangeable password can be exploited by remote attackers to gain full control over the affected devices.

In addition to the root account, there is also a guest account that is created at installation time and which also has an unchangeable static password. However, this account has limited privileges.

Cisco released version 02.04.70 of the software for Cisco Modular Encoding Platform D9036 and users are advised to upgrade as soon as possible. The update won't reset the hard-coded password for the root and guest accounts, but will allow administrators to manually do so from the command line, the company said in another advisory.

The Cisco Unified Computing System (UCS) Manager and the Cisco Firepower 9000 Series appliances contain a CGI script that allows the execution of shell commands and can be accessed without authentication by sending specially crafted HTTP requests.

This vulnerability could allow remote attackers to execute arbitrary commands on the affected devices and is also rated as critical. It was addressed in Cisco UCS Manager versions 2.2(4b), 2.2(5a), and 3.0(2e) and in FX-OS version 1.1.2.